This invention generally relates to fuel injector control systems. More particularly, this invention relates to a strategy for identifying particular fuel injectors to individually control injectors based upon their individual characteristics.
Fuel injectors are often incorporated into vehicle engine systems for providing fuel to the engine. One type of fuel injector includes a spool valve that controls the amount of fuel provided by the injector to the engine. Controlling the spool valve typically is done electronically by selectively powering open and close coils, respectively, to move the spool into the position necessary to achieve the desired fuel flow rate.
Due primarily to manufacturing tolerances, every fuel injector does not perform identically. There are two main performance characteristics that typically vary from injector to injector. These include the injector""s response time to the electrical signals to drive the coils and the actual rate of fuel supplied by the injector. These are often referred to as the gain and offset of the injector.
Because there are variations between injectors, optimum engine performance requires a strategy for specifically controlling each injector to accommodate the individual performance characteristics of each injector. One proposal is shown in U.S. Pat. No. 4,972,293. In that arrangement, a strategy is utilized to identify individual injectors and to then modify the manner in which each injector is controlled to achieve a desired performance. The particular strategy disclosed in that document is somewhat cumbersome.
There is a need for improved strategies for identifying individual injectors and customizing the control of each injector to accommodate for differences between individual injectors. This invention provides a unique way of accomplishing that end.
In general terms, this invention is a fuel injector assembly that accommodates for differences in performance between individual injectors.
A fuel injector assembly designed according to this invention includes at least one coil. In some examples, the injector assembly includes an open coil and a close coil. At least one driver is associated with the coil to selectively power the coil to achieve a desired fuel flow rate through the injector assembly. The coil and driver are housed within a fuel injector housing for each individual injector. A power source that is external to the fuel injector housing provides the power to energize the driver and drive the coil. Each injector includes an energizable voltage or current source within the fuel injector housing that is energized by the external power source and then provides an output that is indicative of the particular characteristics of the fuel injector. The indication provided by the internal, energizable voltage or current source permits the controller of the assembly to customize the signals provided to the individual fuel injectors to accommodate for the particular performance characteristics of each injector.
In one example, the internal, energizable power source is a voltage source. In another example, the internal, energizable power source is a current source.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiments. The drawings that accompany the detailed description can be briefly described as follows.